The aulacid wasps, Aulacidae Shuckard, 1842 are endoparasitoids of wood-boring larvae Coleoptera (Cerambycidae and Buprestidae) and Hymenoptera (Xiphydriidae). The family Aulacidae is small distinct family in the superfamily Evanioidea. This family includes 262 extant species grouped within only two genera, Aulacus Jurine, 1807 with 83 species and Pristaulacus Kieffer, 1900 (including the former Panaulix Benoit, 1984), with 177 species (Jennings and Austin 2004, Turrisi et al. 2009, Chen et al. 2016, Turrisi and Nobile 2016; Turrisi 2017). According to the online Taxapad (Yu et al. 2012) this family contains four subfamilies and 11 genera, including fossils. Some identified fossils are not completely known and their inclusion within Aulacidae still remains somewhat questionable (Zhang and Rasnitsyn 2004).

Some evidence support strongly a close relationship between Aulacidae and Gasteruptiidae and each group are currently considered as distinct families (Jennings and Austin 2000, Turrisi et al. 2009). However, the current generic classification of the Aulacidae is not sufficiently robust and needs further study. There is strong support for the monophyly of Pristaulacus but not for Aulacus, which is largely paraphyletic in the cladistics analyses of Turrisi et al. (2009). The faunistic knowledge of Aulacidae is generally unsatisfactory due to their general rarity and difficulty in collecting by conventional methods, e.g., by net; there is a general paucity of available material, even in the large museums (Turrisi 2007).

The Iranian Aulacidae has been recently treated by Ghahari (2012), Lotfalizadeh et al. (2017) and Ghahari and Madl (2017). Nonetheless, continuous sampling in different ecosystems, particularly with Malaise traps, has resulted in new records which we present in this paper, along with an illustrated key to species.

The specimens examined in the present paper have been recently collected using a modified Malaise-trap (Funnel-Townes Style, B. Motamedinia, unpublished: BM-MTF-TS) placed in various localities of Kermanshah province (Western part of Iran), as well as in Eastern provinces (Fig. 1A–B). The traps were a basic Malaise trap supplemented with an additional internal collecting bottle. The insects bump into the black mesh panel and move towards the lighter mesh to escape due to their positive phototropism (van Achterberg 2009); at this point, they encounter the collection bottle and become permanently trapped. However, a considerable number of insects fail to enter the collecting bottle for various reasons e.g., inappropriate installation of trap or collecting bottle, displacement of the trap by wind, or the particular behavior of the insects (Fig. 1C–D). The collected specimens were killed in 75% ethanol and then glued on triangular cards, according to AXA protocol (van Achterberg 2009). Finally, all of the specimens labeled using new pinning block (Ghafouri Moghaddam et al. 2017).

Specimens were examined under a Nikon^® SMZ645 stereomicroscope (Nikon^® Inc., Japan). Illustrations of taxonomically important body parts were taken using a Canon^® EOS 700D (Canon^® Inc., Japan), a simple light source with halogen lamp (manual) and 2× lenses mounted on Hund^® Stereomicroscope (Wetzlar Inc., Germany). Multiple images were subsequently processed in Zerene Stacker^TM version 1.04 software and post processed in Adobe Photoshop^® CS6. The images in the illustrated key were prepared by the second author using voucher specimens already deposited in his private collection. Morphological terminology follows Crosskey (1951), Huber and Sharkey (1993) and Turrisi (2007). Terminology for surface sculpturing follows Harris (1979). A distributional map was generated using SimpleMappr (Shorthouse 2010) and collecting localities are given in Fig. 8. The following abbreviations are used for depositories: CPTO: Guido Pagliano collection, Torino, Italy; DPPZ: Collection of Department of Plant Protection, University of Zabol, Iran; DU: Depository Unknown; MCSN: Museo Civico di Storia Naturale “G. Doria”, Genova, Italy; MNHN: Muséum National d’Histoire Naturelle, Laboratoire d’Entomologie, Paris, France; MNHN: Naturhistorisches Museum, Wien, Austria; ZIN: Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia; ZMUC: Zoological Museum, Copenhagen University, Denmark.

Measurements were done with a micro-ruler. Morphometric ratios were measured in tpsDig ver. 2.05 (Rohlf 2006), using digitized coordinates of landmarks and capture outlines. It should be noted that we documented measurements to the nearest 0.001 mm with tpsDig, but we conservatively report them to an accuracy of two decimal places. Definitions and abbreviations for the measured characters are shown in Table 1 (see also Figs 2, 3, 5).

Five species belonging to the genus Pristaulacus are recorded from five provinces of Iran (East-Azarbaijan, Guilan, Kermanshah, Shiraz and West Azarbaijan) (Fig. 8). The species recorded for the first time from Iran and from individual provinces are marked with a single (*) or double (**) asterisks, respectively. It should be noted that no depository was mentioned for specimens of both P. barbeyi and P. galitae from Iran (Ghahari 2012), thus, it has not been possible to examine this material for confirmation. These taxa are marked below with an #.

The number of Iranian Aulacidae is raised to five, all within a single genus (Pristaulacus). All these species have been collected in Northern and Northwestern (forest habitat) regions, except P. compressus, which is recorded from Southern (subdesertic habitat) region.

Jennings et al. (2004) stated that remnant stands of forest are an ideal habitat for their wood-boring hosts. These wasps can be locally abundant in areas undergoing logging or forest fires. The rich fossil record of Aulacidae indicates they were quite abundant in the Mesozoic (Jennings and Austin 2004, Turrisi et al. 2009).

The new specimens have been collected in Zagros forests, which have an area of about 6 million hectares (3.5 percent of Iran), located in the west of Iran with a semi-arid to temperate climate. This wide territory is also referred to as western oak forests (oak-woodland), due to the dominancy of oak species (Quercus spp.). The species composition of the woodland vegetation depends on the climatic conditions (Zohary 1973, Kwandrans 2007).

The five species reported in this paper are distributed only in the Western part of the Palearctic region. The results of the present study clearly show the improved efficiency of modern collecting methods for Hymenoptera that are rarely collected with most conventional methods. In addition, the best collecting period seems to be June and this is consistent with those reported in Lotfalizadeh et al. (2017).

Although the research suggests a higher number of species in the Western territories of Iran we predict that the Eastern and Southern parts should also be quite species-rich. Further investigation, especially in poorly collected regions will probably increase the number of known species (Turrisi 2014). The species reported from Iran have ranges included in the Western part of the Palaearctic region. Given the poorly known faunistic situation, it is premature to discuss possible relationships among faunas of Iran and adjacent territories.